source: fedd/access_to_abac.py @ cedf721

#!/usr/bin/env python

import sys, os
import re
import subprocess
import os.path

from string import join
from optparse import OptionParser, OptionValueError
from tempfile import mkdtemp

from federation.fedid import fedid
from federation.authorizer import abac_authorizer
from federation.util import abac_split_cert, abac_pem_type, file_expanding_opts


class attribute:
    '''
    Encapculate a principal/attribute/link tuple.
    '''
    bad_attr = re.compile('[^a-zA-Z0-9_]+')
    def __init__(self, p, a, l=None):
        self.principal = p
        self.attr = attribute.bad_attr.sub('_', a)
        if l: self.link = attribute.bad_attr.sub('_', l)
        else: self.link = None

    def __str__(self):
        if self.link:
            return "%s.%s.%s" % (self.principal, self.attr, self.link)
        elif self.attr:
            return "%s.%s" % (self.principal, self.attr)
        else:
            return "%s" % self.principal

class credential:
    '''
    A Credential, that is the requisites (as attributes) and the assigned
    attribute (as principal, attr).   If req is iterable, the requirements are
    an intersection/conjunction.
    '''
    bad_attr = re.compile('[^a-zA-Z0-9_]+')
    def __init__(self, p, a, req):
        self.principal = p
        if isinstance(a, (tuple, list, set)) and len(a) == 1:
            self.attr = credential.bad_attr.sub('_', a[0])
        else:
            self.attr = credential.bad_attr.sub('_', a)
        self.req = req

    def __str__(self):
        if isinstance(self.req, (tuple, list, set)):
            return "%s.%s <- %s" % (self.principal, self.attr, 
                    join(["%s" % r for r in self.req], ' & '))
        else:
            return "%s.%s <- %s" % (self.principal, self.attr, self.req)

# Mappinng generation function and the access parser throw these when there is
# a parsing problem.
class parse_error(RuntimeError): pass

# Error creating a credential
class credential_error(RuntimeError): pass

# Functions to parse the individual access maps as well as an overall function
# to parse generic ones.  The specific ones create a credential to local
# attributes mapping and the global one creates the access policy credentials.

#  All the local parsing functions get the unparsed remainder of the line
#  (after the three-name and the attribute it maps to), the credential list to
#  add the new ABAC credential(s) that will be mapped into the loacl
#  credentials, the fedid of this entity, a dict mapping the local credentials
#  to ABAC credentials that are required to exercise those local rights and the
#  three-name (p, gp, gu) that is being mapped.
def parse_emulab(l, creds, me, to_id, p, gp, gu, lr):
    '''
    Parse the emulab (project, allocation_user, access_user) format.  Access
    users are deprecates and allocation users used for both.  This fuction
    collapses them.
    '''
    right_side_str = '\s*,\s*\(\s*%s\s*,\s*%s\s*,\s*%s\s*\)' % \
            (id_same_str, id_same_str,id_same_str)

    m = re.match(right_side_str, l)
    if m:
        project, user = m.group(1,2)
        # Resolve "<same>"s in project and user
        if project == '<same>':
            if gp  is not None:
                project = gp 
            else:
                raise parse_error("Project cannot be decisively mapped: %s" % l)
        if user == '<same>':
            if gu is not None:
                user = gu 
            else:
                raise parse_error("User cannot be decisively mapped: %s" % l)

        # Create a semi-mnemonic name for the destination credential (the one
        # that will be mapped to the local attributes
        if gp and gu:
            a = 'project_%s_user_%s' % (gp, gu)
        elif gp:
            a = 'project_%s' % gp
        elif gu:
            a = 'user_%s' % gu
        else:
            raise parse_error("No mapping for %s/%s!?" % (gp, gu))

        # Store the creds and map entries
        c = credential(me, a, 
                [attribute(p, x, lr) for x in (gp, gu) if x is not None])
        creds.add(c)
        if (project, user) in to_id: to_id[(project,user)].append(c)
        else: to_id[(project,user)] = [ c ]
    else:
        raise parse_error("Badly formatted local mapping: %s" % l)


def parse_protogeni(l, creds, me, to_id, p, gp, gu, lr):
    '''
    Parse the protoGENI (cert, user, user_key, cert_pw) format.
    '''
    right_side_str = '\s*,\s*\(\s*(%s)\s*,\s*(%s)\s*,\s*(%s)\s*,\s*(%s)\s*\)' \
            % (path_str, id_str, path_str, id_str)

    m = re.match(right_side_str, l)
    if m:
        cert, user, key, pw = m.group(1,2,3,4)
        # The credential is formed from just the path (with / mapped to _) and
        # the username.
        acert = re.sub('/', '_', cert)

        a = "cert_%s_user_%s" % (acert, user)

        # Store em
        c = credential(me, a, 
                [attribute(p, x, lr) for x in (gp, gu) if x is not None])
        creds.add(c)
        if (cert, user, key, pw) in to_id: 
            to_id[(cert, user, key, pw)].append(c)
        else: 
            to_id[(cert, user, key, pw)] = [ c ]
    else:
        raise parse_error("Badly formatted local mapping: %s" % l)

def parse_dragon(l, creds, me, to_id, p, gp, gu, lr):
    '''
    Parse the dragon (repository_name) version.
    '''
    right_side_str = '\s*,\s*\(\s*(%s)\s*\)' % \
            (id_str)

    m = re.match(right_side_str, l)
    if m:
        repo= m.group(1)
        c = credential(me, 'repo_%s' % repo, 
                [attribute(p, x, lr) for x in (gp, gu) if x is not None])
        creds.add(c)
        if repo in to_id: to_id[repo].append(c)
        else: to_id[repo] = [ c ]
    else:
        raise parse_error("Badly formatted local mapping: %s" % l)

def parse_skel(l, creds, me, to_id, p, gp, gu, lr):
    '''
    Parse the skeleton (local_attr) version.
    '''
    right_side_str = '\s*,\s*\(\s*(%s)\s*\)' % \
            (id_str)

    m = re.match(right_side_str, l)
    if m:
        lattr = m.group(1)
        c = credential(me, 'lattr_%s' % lattr, 
                [attribute(p, x, lr) for x in (gp, gu) if x is not None])
        creds.add(c)
        if lattr in to_id: to_id[lattr].append(c)
        else: to_id[lattr] = [ c ]
    else:
        raise parse_error("Badly formatted local mapping: %s" % l)

# internal plug-ins have no local attributes.
def parse_internal(l, creds, me, to_id, p, gp, gu, lr): pass


def parse_access(fn, mapper, delegation_link):
    """
    Parse the access file, calling out to the mapper to parse specific
    credential types.  Mappers are above this code.
    """
    creds = set()
    to_id = { }
    f = open(fn, "r")
    for i, l in enumerate(f):
        try:
            if comment_re.match(l):
                continue
            else:
                m =  line_re.match(l)
                if m:
                    p, da = m.group(1, 4)
                    gp, gu = m.group(2, 3)
                    if gp == '<any>': gp = None
                    if gu == '<any>': gu = None

                    creds.add(credential(me, da, 
                            [attribute(p, x, delegation_link) \
                                    for x in (gp, gu) \
                                        if x is not None]))
                    if m.group(5) and mapper:
                        mapper(m.group(5), creds, me, to_id, p, gp, gu,
                                delegation_link)
                else:
                    raise parse_error('Syntax error')
        except parse_error, e:
            f.close()
            raise parse_error('Error on line %d of %s: %s' % \
                    (i, fn, e.message))
    f.close()

    return creds, to_id



class access_opts(file_expanding_opts):
    '''
    Parse the options for this program.  Most are straightforward, but the
    mapper uses a callback to convert from a string to a local mapper function.
    '''
    # Valid mappers
    mappers = { 
            'emulab': parse_emulab, 
            'dragon': parse_dragon,
            'internal': parse_internal,
            'skel': parse_skel,
            'protogeni': parse_protogeni,
            }

    @staticmethod
    def parse_mapper(opt, s, val, parser, dest):
        if val in access_opts.mappers:
            setattr(parser.values, dest, access_opts.mappers[val])
        else:
            raise OptionValueError('%s must be one of %s' % \
                    (s, join(access_opts.mappers.keys(), ', ')))

    def __init__(self):
        file_expanding_opts.__init__(self, usage='%prog [opts] file [...]')
        self.add_option('--cert', dest='cert', default=None,
                type='str', action='callback', callback=self.expand_file,
                help='my fedid as an X.509 certificate')
        self.add_option('--key', dest='key', default=None,
                type='str', action='callback', callback=self.expand_file,
                help='key for the certificate')
        self.add_option('--dir', dest='dir', default=None,
                type='str', action='callback', callback=self.expand_file,
                help='Output directory for credentials')
        self.add_option('--type', action='callback', nargs=1, type='str',
                callback=access_opts.parse_mapper, 
                callback_kwargs = { 'dest': 'mapper'}, 
                help='Type of access file to parse.  One of %s. ' %\
                        join(access_opts.mappers.keys(), ', ') + \
                        'Omit for generic parsing.')
        self.add_option('--quiet', dest='quiet', action='store_true', 
                default=False,
                help='Do not print credential to local attribute map')
        self.add_option('--no_create_creds', action='store_false', 
                dest='create_creds', default=True,
                help='Do not create credentials for rules.')
        self.add_option('--file', dest='file', default=None,
                type='str', action='callback', callback=self.expand_file,
                help='Access DB to parse.  If this is present, ' + \
                        'omit the positional filename')
        self.add_option('--mapfile', dest='map', default=None,
                type='str', action='callback', callback=self.expand_file,
                help='File for the attribute to local authorization data')
        self.add_option('--no-delegate', action='store_false', dest='delegate',
                default=True,
                help='do not accept delegated attributes with the ' +\
                        'acting_for linking role')
        self.add_option('--no_auth', action='store_false', dest='create_auth', 
                default=True, help='do not create a full ABAC authorizer')
        self.add_option('--debug', action='store_true', dest='debug', 
                default=False, help='Just print actions')
        self.set_defaults(mapper=None)

def create_creds(creds, cert, key, dir, debug=False, 
        creddy='/usr/local/bin/creddy'):
    '''
    Make the creddy calls to create the attributes from the list of credential
    objects in the creds parameter.
    '''
    def attrs(r):
        '''
        Convert an attribute into creddy --subject-id and --subject-role
        parameters
        '''
        if r.principal and r.link and r.attr:
            return ['--subject-id=%s' % r.principal, 
                    '--subject-role=%s.%s' % (r.attr, r.link),
                    ]
        elif r.principal and r.attr:
            return ['--subject-id=%s' % r.principal, 
                    '--subject-role=%s' %r.attr]
        elif r.principal:
            return ['--subject-id=%s' % r.prinicpal]
        else:
            raise parse_error('Attribute without a principal?')

    # main line of create_creds
    for i, c in enumerate(creds):
        cmd = [creddy, '--attribute', '--issuer=%s' % cert, '--key=%s' % key,
                '--role=%s' % c.attr, '--out=%s/cred%d_attr.der' % (dir, i)]
        for r in c.req:
            cmd.extend(attrs(r))
        if debug:
            print join(cmd)
        else:
            rv = subprocess.call(cmd)
            if rv != 0:
                raise credential_error("%s: %d" % (join(cmd), rv))

def clear_dir(dir):
    for path, dirs, files in os.walk(dir, topdown=False):
        for f in files: os.unlink(os.path.join(path, f))
        for d in dirs: os.rmdir(os.path.join(path, d))

# Regular expressions and parts thereof for parsing
comment_re = re.compile('^\s*#|^$')
fedid_str = 'fedid:([0-9a-fA-F]{40})'
id_str = '[a-zA-Z][\w_-]*'
path_str = '[a-zA-Z_/\.-]+'
id_any_str = '(%s|<any>)' % id_str
id_same_str = '(%s|<same>)' % id_str
left_side_str = '\(\s*%s\s*,\s*%s\s*,\s*%s\s*\)' % \
        (fedid_str, id_any_str, id_any_str)
right_side_str = '(%s)(\s*,\s*\(.*\))?' % (id_str)
line_re = re.compile('%s\s*->\s*%s' % (left_side_str, right_side_str))

p = access_opts()
opts, args = p.parse_args()

cert, key = None, None
delete_certs = False
delete_creds = False

if opts.file:
    args.append(opts.file)

# Validate arguments
if len(args) < 1:
    sys.exit('No filenames given to parse')

if opts.key:
    if not os.access(opts.key, os.R_OK):
        key = opts.key
    else:
        sys.exit('Cannot read key (%s)' % opts.key)

if opts.dir:
    if not os.access(opts.dir, os.F_OK):
        try:
            os.mkdir(opts.dir, 0700)
        except EnvironmentError, e:
            sys.exit("Cannot create %s: %s" % (e.filename, e.strerror))
    if not os.path.isdir(opts.dir):
        sys.exit('%s is not a directory' % opts.dir)
    elif not os.access(opts.dir, os.W_OK):
        sys.exit('%s is not writable' % opts.dir)

if opts.create_auth:
    creds_dir = mkdtemp()
    delete_creds = True
    auth_dir = opts.dir
else:
    creds_dir = opts.dir
    auth_dir = None

if opts.delegate: delegation_link = 'acting_for'
else: delegation_link = None

if not opts.mapper and (opts.map or opts.debug):
    print >>sys.stderr, "No --type specified, mapping file will be empty."

if opts.cert: 
    try:
        me = fedid(file=opts.cert) 
    except EnvironmentError, e:
        sys.exit('Bad --cert: %s (%s)' % (e.strerror, e.filename or '?!'))

    if not opts.key:
        if abac_pem_type(opts.cert) == 'both':
            key, cert = abac_split_cert(opts.cert)
            delete_certs = True
    else:
        cert = opts.cert
else: 
    print >>sys.stderr, 'No --cert, using dummy fedid'
    me = fedid(hexstr='0123456789012345678901234567890123456789')
    cert = None

# The try block makes sure that credentials split into tmp files are deleted
try:
    # Do the parsing
    for fn in args:
        try:
            creds, to_id = parse_access(fn, opts.mapper, delegation_link)
        except parse_error, e:
            print >> sys.stderr, "%s" % e
            continue

        except EnvironmentError, e:
            print >>sys.stderr, "File error %s: %s" % \
                    (e.filename or '!?', e.strerror) 
            continue

        # Credential output
        if opts.create_creds:
            if all([cert, key, opts.dir]):
                try:
                    create_creds([c for c in creds if c.principal == me],
                            cert, key, creds_dir, opts.debug)
                except credential_error, e:
                    sys.exit('Credential creation failed: %s' % e)
            else:
                print >>sys.stderr, 'Cannot create credentials.  ' + \
                        'Missing parameter'

        # Local map output
        if opts.map or opts.debug:
            try:
                if opts.map and opts.map != '-' and not opts.debug:
                    f = open(opts.map, 'w')
                else:
                    f = sys.stdout
                for k, c in to_id.items():
                    # Keys are either a single string or a tuple of them; join
                    # the tuples into a comma-separated string.
                    if isinstance(k, basestring): rhs = k
                    else: rhs = join(k, ', ')

                    for a in set(["%s.%s" % (x.principal, x.attr) for x in c]):
                        print >>f, "%s -> (%s)" % (a, rhs)
            except EnvironmentError, e:
                sys.exit("Cannot open %s: %s" % (e.filename or '!?', 
                    e.strerror))

        # Create an authorizer if requested.
        if opts.create_auth:
            clear_dir(auth_dir)
            try:
                # Pass in the options rather than the potentially split key
                # because abac_authorizer will split it and store it
                # internally.  The opts.cert may get split twice, but we won't
                # lose one.
                a = abac_authorizer(key=opts.key, me=opts.cert, 
                        certs=creds_dir, save=auth_dir)
                a.save(auth_dir)
            except EnvironmentError, e:
                sys.exit("Can't create or write %s: %s" % \
                        (e.filename, e.strerror))
            except abac_authorizer.bad_cert_error, e:
                sys.exit("Error creating authorizer: %s" % e)

finally:
    try:
        if delete_certs:
            if cert: os.unlink(cert)
            if key: os.unlink(key)
        if delete_creds and creds_dir:
            clear_dir(creds_dir)
            os.rmdir(creds_dir)
    except EnvironmentError, e:
        sys.exit("Can't remove %s: %s" % ( e.filename, e.strerror))